PERGANDE — NORTH AMERICAN PHYLLOXERIN^. 193 



Refmarkable it is, however, that the irritation is not coniined to 

 the lower side of the leaf but that it extends also to the upper 

 surface, to the opposite pore, producing a counterpart of that on 

 the underside. Both sides of the young gall at this stage are reg- 

 ularly conical and are fringed at the apex of each cone by about 

 eight or nine very long, slender, backward curved, fleshy filaments 

 which, when compared with the hairs surrounding the other 

 pores, prove them to be identical though greatly enlarged. When 

 some of the galls were opened it was found that they were divided 

 horizontally by a delicate membrane into two compartments in 

 the lower one of which the young stem-mother, already mature 

 at this date, and surrounded by some eggs, had established her 

 home. With her was also found but one cast skin, which seemed 

 to indicate that several skins had been cast before the gall had 

 formed and closed. The color of the young gall above is quite 

 pale green with the filaments bright cherry or pink. The lower 

 side is darker and the filaments white. 



Two weeks later the galls had changed so completely in appear- 

 ance that they could scarcely be recognized as belonging to the 

 same species were it not for the filaments fringing the apex of the 

 nipples, and even these were mere rudiments, much reduced by 

 drying up. They were then fully mature and some of them 

 already empty. When cut vertically it was observed that the 

 dividing membrane had entirely disappeared, except the before- 

 mentioned rudiment at the circumference. 



Phylloxera c. -septum, var. perforans n. var. 

 Plate I., Figs, 7-8; Plate X., figs. 57-60. 



A very conspicuous form of the above gall has been occasion- 

 ally observed in the vicinity of Washington for several years past, 

 occurring usually upon the leaves of Hicoria glabra, though 

 always when already deserted. This same form had previously 

 been observed by Dr. A. Fitch in the state of New York, also when 

 deserted. In the place of the rightful occupants he discovered 

 the imago and larvae of a Phloeothrips, to which he gave the 

 name of Phleothrips caryce (Third Rep. on the Nox. and Ben. Ins. 

 of N. Y., p. 127, No. 165), which he, however, hesitated, and cor- 

 rectly so, to consider as the true architect of these singular galls. 



During May of 1890 1 have been fortunate, however, to discover 



